DE3688841T2 - LOW INTERFERON DOSAGE FOR INCREASING VACCINE EFFECTIVENESS. - Google Patents

Abstract

A biologically active interferon can be administered to an animal in conjunction with the administration of a vaccine to improve the vaccine efficiency and allow the use of a smaller vaccination dose. This procedure will cause a less severe vaccine infection in the animal than if no interferon was administered.

Description

The invention relates generally to combinations which increase the efficacy of vaccines in warm-blooded vertebrates. They involve the administration of interferon to a warm-blooded vertebrate together with the administration of a vaccine.

The term "interferon" generally covers a group of vertebrate glycoproteins and proteins which are known to have various biological activities such as antiviral, antiproliferative and immunomodulatory activities in the animal species from which such substances are derived. The following definition for interferon was accepted by an international committee that met to develop a system for the proper nomenclature of interferon: "To qualify as an interferon, a factor must be a protein that exerts virus-nonspecific antiviral activity at least in homologous cells via cellular metabolic processes including the synthesis of both RNA and protein." Journal of Interferon Research, 1, page vi (1980).

Since the first descriptions of interferon by Isaacs and Lindeman [see, Proc. Rov. Soc. London (Ser. B), volume 147, page 258 et seq. (1957) and US-A-3,699,222], interferon has been the subject of intensive research worldwide. Publications concerning the synthesis of interferon; M. Wilkinson and AG Morris, Interferon and the Immune System 1: Induction of Interferon by Stimulation of the Immune System, Interferons: From Molecular Biology to Clinical Application, eds.: DC Burke and AG Morris, Cambridge Univ. Press, 1983, pages 149-179; PI Marcus, chap. 10, Interferon Induction by Virus, Interferons and Their Applications, eds.: PE Came and WA Carter, Springer Verlag, (Handbook of Experimental Pharmacology V. 71) 1984, pp. 205-232; its proposed molecular characterizations; PB Sehgal, How Many Human Interferons Are There? Interferon 1982, ed. I. Gresser, Academic Press, 1982, pp. 1-22; J. Collins, Structure and Expression of the Human Interferon Genes, Interferons: From Molecular Biology to Clinical Application, eds.: DC Burke and AG Morris, Cambridge Univ. Press, 1983, pp. 35-65; KC Zoon and R. Wetzel, chap. 5, Comparative Structures of Mammalian Interferons, 1a: Interferons and Their Applications, Ed: PE Came and WA Carter, Springer Verlag, (Handbook of Experimental Pharmacology V. 71) 1984, pages 79-100; his clinical Applications; M. Krim, Chapter 1, Interferons and Their Applications: Past, Present and Future, Interferons and Their Applications, eds.: PE Came and WA Carter, Springer Verlag, (Handbook of Experimental Pharmacology V. 71) 1984; SB Greenberg and MW Harmon, Chapter 21, Clinical Use of Interferons: Localized Applications in Viral Diseases, Ibid. pp. 433-453; and proposed mechanisms of its antitumor, antiviral and immune system activities; GM Scott, The Antiviral Effects of Interferon, From Molecular Biology to Clinical Application, eds.: DC Burke and AG Morris, Cambridge Univ. Press, 1983, pp. 279-311; M. McMahon and IM Kerr, The Biochemistry of the Antiviral State, Ibid. pp. 89-108; JS Malpas, The Antitumor Effects of Interferon, Ibid. Pages 313-327; J. Taylor-Papadimitrion, The Effects of Interferon on the Growth and Function of Normal and Malignant Cells, Ibid. Pages 109-147.

Because of the intensity and separate origins of research on interferon and its properties and uses, there is a significant lack of uniformity regarding such issues as the classification of interferon types. There are also numerous, sometimes conflicting, theories regarding the mechanism of action of interferon in producing clinical effects. The following brief summary of the current state of knowledge regarding interferon will aid in understanding the subject matter of the present invention.

Although originally isolated from avian cells (chicken allantoic cells), interferon production has been observed in cells of all vertebrate classes, including mammals, amphibians, and reptiles. Interferon production by vertebrate cells is rare and spontaneous but is often readily induced by treatment of cells (in vivo or in vitro) with a variety of substances, including viruses, nucleic acids (including those of viral origin as well as synthetic polynucleotides), lipopolysaccharides, and various antigens and mitogens.

Interferons have been generally named by reference to the type of animal cells producing the substance (e.g., human, mouse, or bovine), the type of cell involved (e.g., leukocyte, lymphoblastoid, fibroblast), and occasionally the type of inducing material responsible for interferon production (e.g., viral, immune). Interferon has been loosely classified by some investigators according to the mode of induction as either Type I or Type II, with the former referring to interferon induced by viruses and nucleic acid, and the latter referring to the lymphokine produced by induction. by antigens and mitogens. Recently, the International Committee developing a proper nomenclature system for interferon has classified interferon into two types on the basis of antigenic specificities. In this newer classification, the names alpha (α), beta (β), and gamma (γ) have been used, corresponding to the earlier names leukocyte, fibroblast, and type II (immune) interferons, respectively. Alpha and beta interferons are usually acid stable and correspond to the so-called type I interferons; gamma interferons are usually acid labile and correspond to the so-called type II interferons. The nomenclature recommendations of the International Commission apply only to human and mouse interferons. Journal of Interferon Research, 1 page vi (1980).

Determination of the precise molecular structures for interferon has been beyond the capabilities of the field for some time. In the years since interferon was first characterized as protein-like due to its inactivation by trypsin, attempts to purify and uniquely characterize it have been thwarted by its high specific activity as well as its apparent heterogeneity. At present, some degree of precision in determining the molecular structure for interferon has been achieved. See P. B. Sehgal, supra; J. Collins, supra; and K. C. Zoon and R. Wetzel, supra.

In its earliest applications, interferon was used exclusively as an antiviral agent, and the most successful clinical therapeutic applications to date have been in the treatment of viral or virus-related disease states. However, it became apparent that exogenous interferon could sometimes induce regression or remission of various metastatic diseases. A review of current clinical trials of interferon as an antiviral and antiproliferative therapeutic agent up to 1983 is included in The Biology of the Interferon System 1983, Proceedings of the Second International TNO Meeting on the Biology of the Interferon System, Rotterdam, The Netherlands, 18-22 April 1983, and Antiviral Research, March 1983, Special Abstract Issue, Elsevier/North-Holland Biomedical Press, Netherlands.

The clinical agent of choice in this work was human leukocyte interferon, which was mass produced by procedures including the collection and purification of large quantities of human leukocyte clots, induction with viruses, and isolation from culture media. The need for interferon of human origin is of course in line with the long-standing Conclusion that interferon is "species-specific", ie, is biologically active in vivo only in species homologous to the source of cells.

In the work described above, interferon was administered parenterally, i.e., intramuscularly and intradermally, with some successful topical and intranasal uses described. It was administered intravenously because of significant adverse effects due to impurities in crude and even highly purified isolates. Applicant's invention, described in US-A-4,462,985 and in PCT International Application No. PCT/US 81/01103, relates to the use of interferon from heterologous species and also relates to the oral administration of interferon. Prior to these disclosures, there were no reports of therapeutically successful oral administration of interferon. This was consistent with the widely held belief that interferon would not withstand exposure to a digestive environment such as that found in mammals.

In addition to its use in antiviral and antitumor therapy, interferon has recently been found to have immunomodulatory effects of both immunopotentiating and immunosuppressive nature. B. Lebleu and J. Content, Mechanisms of Interferon Action: Biochemical and Genetic Approaches, Interferon 1982, ed.: I. Gresser, Academic press, 1982, pp. 47-94; M. Moore, Interferon and the Immune System, 2: Effect of IFN on the Immune System, Interferons: From Molecular Biology to Clinical Application, ed.: D. C. Burke and A. G. Morris, Cambridge Univ. Press, 1983, pp. 181-209; H. Smith-Johannsen, Y-T Hou, X-T Liu, and Y-H Tan, Chapter 6, Regulatory Control of Interferon Synthesis and Action, Interferons and their Applications, eds.: P. E. Came and W. A. Carter, Springer Verlag, (Handbook of Experimental Pharmacology V. 71) 1984, pp. 101-135; J. L. Raylor, J. L. Sabram, and S. E. Grossberg, Chapter 9, The Cellular Effects of Interferon, Ibid. Pages 169-204; J. M. Zarling, Effects of Interferon and its Inducers on Leukocytes and Their Immunologic Functions, Ibid. Pages 403-431; R. Ravel, The Interferon System in Man: Nature of the Interferon Molecules and Mode of Action, Antiviral Drugs and Interferon: The Molecular Basics of Their Activity, Ed.: Y. Becker, Martinus Nijhoff Pub., 1984, pages 357-433.

Furthermore, "new" biological activities for exogenous and endogenous interferon are constantly being identified. K. Berg, M. Hokland, and I. Heron, Biological Activities of Pure HuIFN-Alpha Species, Interferon, Properties, Mode of Action, Production, Clinical Application, eds.: K. Munk and H. Kirchner, (Beiträge zur Onkologie V. 11) pages 118-126; S. Pestka et al., The Specific Molecular Activities of Interferons Differ for Antiviral, Antiproliferative and Natural Killer Cell Activities, The Biology of the Interferon System, 1983, eds.: E. DeMaeyer and H. Schellekens, pages 535-549; PK Weck and PE Cane, Chapter 16, Comparative Biologic Activities of Human Interferons, Interferons and Their Applications, eds.: PE Came and WA Carter, Springer Verlag, (Handbook of Experimental Pharmacology V. 71) 1984, pages 339-355.

One infectious disease that has not yet been controlled by interferon or other agents is bovine respiratory disease complex (BRDC). BRDC is a catch-all term describing an acute infectious infection of cattle characterized by inflammation of the upper respiratory tract and trachea. BRDC results in pneumonia with clinical signs of dyspnea, anorexia, fever, weakness, mucopurulent nasal discharge, and mucopurulent ocular discharge, all of which result in high morbidity and mortality. BRDC is a major cause of disease-related loss in breeding cattle. The economic loss to the cattle producer for treatment, weight loss, loss from death, and culling is estimated at $333,000,000 annually (National Cattlemen's Association, 1980).

When BRDC symptomatology is observed in cattle after transport to the barns or pastures, it is commonly called "ship fever." On their way to the barns, calves are exposed to stressors from intensive handling techniques, transport without feed or water, and a variety of infectious agents. After arrival at the barns, processing subjects calves to additional stressors from weaning, castration, dehorning, branding, ear marking, deworming, vaccination, and delousing. In many situations, calves are further stressed by changes in nutritional and environmental factors.

The infectious agents to which calves are exposed upon entry into the farm system include viruses (infectious bovine rhinotracheitis (IBR), non-IBR herpesviruses, parainfluenza type 3 (PI3), bovine viral diarrhea (BVD), respiratory syncytial viruses, adenoviruses, enteroviruses, rhinoviruses, parvoviruses, and reoviruses), bacteria (Pasteurella hemolvtica, Pasteurella multocida, and Hemophilus somnus), mycoplasmas (M. dispar, M. bovirhinis, M. bovis, M. arginini), and chlamydia.

The IBR, BVD and PI3 viruses are 3 of the infectious pathogens that are most most commonly isolated by veterinary diagnostic laboratories in cases of BRDC. While several commercially available vaccines are available against IBR, BVD and PI3, they have not been entirely satisfactory in the past, in part because vaccination of calves stressed by shipping can exacerbate clinical signs of the disease. Also, some calves do not develop antibodies after vaccination, leaving them still susceptible to the disease. Furthermore, many commercially available vaccines are designed not to provide protection until 14 days after vaccination, according to the U.S. Department of Agriculture, Bureau of Biologics immunogenicity test. Because of the incompleteness of the vaccination regimens used in the past and the enormous economic losses associated with them, there is a need for improved methods to prevent and treat bovine respiratory disease.

In a more general sense, there is a need for improved methods of vaccinating cattle and other warm-blooded vertebrates. Current vaccines are sometimes harmful. For example, they can cause a harmful vaccine infection. If the efficiency of vaccines could be improved, then perhaps the amount of killed or attenuated microorganisms required to achieve an effective vaccine dose could be reduced. This, in turn, would lower the chances of a harmful vaccine infection and reduce the cost of the vaccine. The possibility of generating a more rapid antibody response to vaccination would also exist.

The applicants have made the surprising discovery that the administration of a biologically active interferon together with the administration of a vaccine can increase vaccination efficacy.

A combination according to the invention for vaccinating a warm-blooded vertebrate comprises a vaccine for inducing immunity against an infectious disease and at least one dose of a biologically active interferon in a dosage form for oral administration in an amount of not more than 5 IU of interferon/lb (11 IU/kg) of body weight of the vertebrate per dosage unit, wherein the combination of the vaccine and the dose of interferon are optionally in a form for separate administration. The presently preferred dose is about 1.0 IU of human alpha interferon per pound of body weight per day.

Furthermore, the present application relates to a method for producing a preparation for oral use in a method for increasing of vaccine efficacy in a warm-blooded vertebrate, the method of manufacture being characterized by combining interferon and a pharmaceutically acceptable carrier for oral administration, the interferon being present in an amount of not more than 5 IU/lb (11 IU/kg) of body weight of the vertebrate.

The interferon is administered orally to the animal. It can be administered in a single dose either simultaneously with the administration of the vaccine or within one day before or after vaccine administration. Alternatively, the interferon can be administered in multiple doses, for example, by administering a dose on two or more days in the period of the day before vaccine administration, the day of vaccine administration and the day after vaccine administration. When the interferon and vaccine are administered simultaneously, they can be administered separately or mixed together. The advantages of the present invention include increased vaccine efficacy by promoting antibody production, earlier antibody production and reduced vaccination costs as a result of using a smaller amount of microorganisms to produce an effective dose. As an example of the latter advantage, current IBR vaccine doses are about 105.5 to 106.0 TCD50/ml. The applicants believe that the present invention should allow a reduction of this dose by a factor of about 10 to 100.

The present invention achieves these effects with low doses of interferon. In addition to the favorable biological activity, the use of small doses of course makes this method less expensive than if large doses were used. Combinations according to the invention are applicable to animal species such as cattle, pigs, goats, sheep, birds, cats, dogs and horses, as well as to humans.

The interferon administered may be of heterologous or homologous origin. ("Heterologous origin" means that the interferon is derived from cells of a species different from the species to which it is administered.) The optimal dose of interferon varies somewhat from species to species and possibly from animal to animal. Also, effects similar to those achieved by a given daily dose administered for a given number of days may be achieved by administering a slightly lower dose for a slightly longer number of days or a slightly higher dose for a slightly shorter number of days. According to the Following the same principles, if an animal has an infection that causes its natural secretion of certain amounts of interferon, the dose to be administered can be slightly reduced to achieve the same biological effects.

The applicants have filed several previous patent applications relating to methods of using interferon (US-A-4,462,985 and US-A- 4,497,795 and US-A-4,820,515 corresponding to DE-A-3 600 083).

The combination preparations of the invention may use interferons produced by methods known to those skilled in the art. A specific suitable method for producing an interferon is described below in Example 1. Examples 2-6 illustrate methods of using interferon. All geometric mean antibody titres are given on the basis of 2 in the following examples.

EXAMPLE 1

Human alpha interferon can be prepared by the following procedure, commonly referred to as the Cantell procedure. The procedure begins with packs of human leukocytes, in this case obtained from the Gulf Coast Regional Blood Center, Houston, Texas. The buffy coats in these packs are pooled in centrifuge tubes and then diluted with 0.83% ammonium chloride. The mixture is incubated for 15 minutes with occasional shaking and then centrifuged for 20 minutes at 2000 rpm. The supernatant is discarded and the cell pellets are resuspended in a minimal volume of sterile phosphate buffered saline (PBS). The mixture is then diluted with ammonium chloride and centrifuged. The supernatant is again discarded and the remaining cell pellets are resuspended with a minimal volume tissue culture medium, such as minimal nutrient medium (MEM) available from KC Biological. Cell concentration is determined using a Coulter counter.

Interferon induction takes place in glass or plastic bottles. The induction medium contains MEM, 75mM Hepes (available from Calbiochem), 75mM Tricine (available from Sigma Chemical Co.), human agamma serum (18 mg/ml), and gentamycin sulfate (from MA Bioproducts; 50 mcg/ml). Cells are added to the induction vessels at a final concentration of approximately 5 to 10 million cells per milliliter. The induction vessel is incubated in a 37ºC water bath and alpha-interferon is added as a primer. After 2 hours, Sendai virus is added to the induction mixture. This causes the production of alpha-interferon in the supernatant by the leukocytes. After a 12-18 hour incubation period, the Induction mixture is centrifuged. The cells are discarded and the supernatant is then purified.

The crude interferon is cooled to 10ºC or below in an ice bath. Five molar potassium thiocyanate is added to obtain a final concentration of 0.5M. This solution is stirred for 15 minutes and then its pH is lowered to 3.3 by the addition of hydrochloric acid. The mixture is then centrifuged at 2800 rpm for 30 minutes and the supernatant is discarded.

The pellets are then resuspended in 95% ethanol and stirred for 15 minutes. This suspension is centrifuged at 2800 rpm for 20 minutes and the pellets are discarded. The pH of the supernatant is then adjusted to 5.8 with sodium hydroxide. The mixture is stirred for 10 minutes and then centrifuged at 2800 rpm for 20 minutes. The pellets are discarded. The pH of the supernatant is then adjusted to 8 with sodium hydroxide. This solution is stirred for 10 minutes and then centrifuged at 2800 rpm for 20 minutes. The supernatant is discarded and the pellets are suspended with 0.5M potassium thiocyanate in a 0.1M sodium phosphate buffer. This suspension is stirred at 4ºC.

Next, the suspension is centrifuged at 2800 rpm for 20 minutes and the pellets are discarded. The pH of the supernatant is adjusted to 5.3 with hydrochloric acid. After stirring and centrifuging for 10 minutes, the pH of the supernatant is adjusted to 2.8 with hydrochloric acid and then stirring is continued for another 20 minutes. This mixture is centrifuged at 2800 rpm and the pellet thus obtained is purified human alpha interferon.

The pellet is resuspended with 0.5M potassium thiocyanate in 0.1M sodium phosphate buffer at pH 8.0. It is then dialyzed against PBS at 4ºC with two changes of PBS. This mixture is then centrifuged and the precipitate is discarded. The remaining purified alpha-interferon is sterilized by filtration through a 0.2 µm filter.

A human alpha interferon is produced according to this process by Immuno Modulators Laboratories, Inc., Stafford, Texas, and sold under the trademark Agriferon®-C for use in cattle.

Other methods known to one skilled in the art are available to produce interferons such as human alpha interferon and human gamma interferon. For example, US-A-4,376,821 and US-A-4,460,685 describe methods for producing human gamma interferon. A method for producing human fibroblast interferon is described in Applicants' US-A-4,462,985.

EXAMPLE 2

Forty veal calves were randomly assigned to four treatment groups of 10 calves each. All calves were initially seronegative for IBR virus. Calves were then given either placebo or human alpha interferon in three consecutive daily doses of 0.1, 1.1, or 11 IU/kg (0.05, 0.5, or 5.0 IU/lb) body weight. One dose of interferon or placebo was given the day before, the day after, and the day of IBR virus inoculation. Each calf was given 103 plaque forming units (PFU) of IBR virus through the nostrils.

Tables 1-3 show the results of this test and are intended to provide background information only. Table 1 Number of calves with a temperature of at least 40ºC (104ºF) Treatment group Days after IBR virus inoculation Control TABLE 2 Geometric mean serum antibody titres to IBR virus Treatment group Days after virus Control TABLE 3 Geometric mean plaque forming unit (PFV) titers of IBR virus excretion Treatment group Days after inoculation Control

As shown in Table 1, the rectal temperatures of the cattle differed significantly among the four treatment groups after inoculation. More calves given the 1.1 IU/kg (0.5 IU/lb) dose than controls had a fever of at least 40ºC (104ºF) 5, 6, 7, 8 and 9 days after inoculation. More control calves had a fever of greater than 40ºC (104ºF) 14 and 18 days after virus inoculation.

Antibodies to the IBR virus were generated in all groups. However, Table 2 shows that antibody production occurred significantly faster in the 1.1 IU/kg (0.5 IU/lb) treated group. Nasal shedding of the IBR virus also occurred and disappeared more quickly in the 1.1 IU/kg (0.5 IU/lb) treated group, as shown in Table 3. Significantly more virus was shed by the 1.1 IU/kg (0.5 IU/lb) treated group than by the control groups at 3 and 7 days after IBR virus inoculation, but significantly less virus was shed 14 days after inoculation. After 14 days, only 7 PFU of virus were shed by the 1.1 IU/kg (0.5 IU/lb) treated calves compared to more than 12,000 PFU of virus shedding from the controls.

In summary, human alpha interferon administered orally at a dose of 1.1 IU/kg (0.5 IU/lb) body weight significantly stimulated antibody development 14 days after IBR virus inoculation and significantly reduced IBR virus rejection 14 days after inoculation.

EXAMPLE 3

A number of low-weight (average weight 208 kg) (460 lbs) beef calves were shipped to a barn and subsequently many experienced a natural outbreak of shipping fever. These calves were not vaccinated. The calves were tested for the presence of antibodies to PI3 virus. The calves that tested seronegative were divided into 3 treatment groups and human alpha interferon or placebo was administered to the 3 groups in 3 consecutive daily oral doses of 0, 0.22 or 2.2 IU/kg (0, 0.1 or 1.0 IU/lb) body weight, respectively. Table 4 shows the results of this test. TABLE 4 Serology for parainfluenza 3 virus 28 days after arrival in the stables Number of seronegative calves Treatment group Seroconversion after 28 days

As shown in Table 4, calves treated with a dose of 0.22 IU/kg (0.1 IU/lb) achieved significantly better seroconversion against PI3 virus during natural disease than calves treated with 2.2 IU/kg (1.0 IU/lb) or with placebo.

EXAMPLE 4

A number of calves were divided into six treatment groups of 18 each. Two of the treatment groups were given a full dose of vaccine, two groups were given a 100-fold reduced dose of vaccine, and the remaining two groups were not vaccinated. For each of the pairs of treatment groups, one group was treated orally with interferon and the other was not treated.

The vaccine was an IBR-PI3-BVD modified live virus vaccine obtained from CEVA Laboratories No. 71020L39 and contained at least 105.7 TCD₅₀/ml IBR virus, 104.3 TCD₅₀/ml BVD virus and 104.7 TCD₅₀/ml PI3 virus. Vaccination was administered intramuscularly. Interferon treatment consisted of a single oral dose of human alpha interferon at 2.2 IU/kg (1.0 IU/lb) body weight and was administered at the time of vaccination. Tables 5-7 show the results of this test. TABLE 5 Geometric mean antibody titres against IBR virus 13 and 25 days after vaccination of seronegative calves Vaccine dose Treatment Number of calves GMT after vaccination per day Placebo Interferon TABLE 6 Geometric mean antibody titres against BVD virus 13 and 25 days after vaccination of seronegative calves Vaccine dose Treatment Number of calves GMT after vaccination per day Placebo Interferon TABLE 7 Seroconversion to PI3 virus 0 and 25 days after inoculation with a full dose of vaccine Calf Treatment PI3 virus antibody titre on day Placebo Interferon

Table 5 shows that the calves treated with interferon produced slightly higher geometric mean IBR virus titers 13 days after vaccination than calves not treated with interferon at an equal vaccination dose. Table 6 shows that the same is also generally true for the geometric mean antibody titer against BVD virus. Table 7 shows a significant improvement in seroconversion in calves treated with interferon versus the control groups. Neither of the two calves (A and B) listed in this table that were not treated with interferon achieved a PI3 virus antibody titer of at least 4 on day 25 after vaccination. However, each of the five calves (C-G) treated with interferon achieved a titer of at least 4 at this time.

EXAMPLE 5

One hundred calves were divided into five treatment groups of 20 each. One group was used as a control and was vaccinated but not treated with interferon. The other four groups were vaccinated and treated with either one dose of lyophilized interferon, two doses of lyophilized interferon, one dose of interferon that was frozen, or two doses of interferon that were frozen. The interferon was human alpha interferon and each oral dose was 2.2 IU/kg (1.0 IU/lb) body weight. Vaccination was carried out as in Example 4. Tables 8-10 show the results of this test. TABLE 8 Geometric mean antibody titres of seronegative calves against IBR virus 14 days after vaccination Treatment 14 days after vaccination Number of calves Number of calves with titres > 8 GMT Control once lyophilized twice lyophilized TABLE 9 Geometric mean antibody titres of seronegative calves against BVD virus 28 days after vaccination Treatment Number of calves GMT Control once lyophilized twice lyophilized once frozen twice frozen TABLE 10 Fever and nausea Number of calves Treatment Fever Peak Duration > 40ºC Days of antibiotic treatment Control once lyophilized twice lyophilized once frozen twice frozen

Table 8 shows that a slightly higher percentage of calves achieved a geometric mean antibody titre against IBR virus of at least 8 on day 14 after vaccination when they were vaccinated with interferon Table 9 shows that all groups treated with interferon produced higher GMT levels of antibodies to BVD virus 28 days later than the control groups. Table 10 shows that most groups of calves treated with interferon had a shorter duration of fever.

EXAMPLE 6

One hundred and two lightweight feedlot steers and bulls (average paid weight 200 kg (442 lbs)) were purchased from a contract buyer in Tennessee. The calves were shipped to Texas and then treated with nothing or with human alpha interferon orally (2.2 IU/kg//1 IU/lb) upon arrival. The next day during treatment, the calves were given an additional 2.2 IU/kg (1 IU/lb) dose of interferon and vaccinated as shown in Table 11. TABLE 11 Number of calves Interferon BVD vaccination twice none never none twice Diamond Labs (killed) never Diamond Labs (killed) twice Nordens MLV TS never Nordens MLV TS

Tables 12-15 show the results of this test. TABLE 12 Number of calves treated with antibiotics for fever >40ºC Treatment BVD vaccination Interferon Number of calves treated on arrival Treatment +1 day Later none twice killed alive TABLE 13 Morbidity and follow-up rates Treatment BVD vaccination Interferon Morbidity rate Follow-up rate none twice killed alive TABLE 14 Duration of fever and peak temperature Number of calves Treatment BVD vaccination Interferon Fever (average) Duration* Peak none twice killed alive * Duration of fever in days ≥40ºC. TABLE 15 Serological response Number of calves Treatment Number of seroconversions GMT of BVD antibody 28 days after vaccination BVD vaccination + interferon BVD vaccination only

Table 12 shows the number of calves in each group treated with antibiotics for fever of at least 40ºC (104ºF). The number is given for the day of arrival, the day of treatment, the day after treatment and finally several days after treatment. As As the "arrival" column shows, significantly more calves in the group vaccinated with live virus and given two doses of interferon were sick before vaccination. This is probably reflected to some extent in the results shown in the tables provided.

Table 13 shows the percentage of morbidity rate, that is, the percentage of calves requiring antibiotic treatment and the percentage of calves requiring follow-up antibiotic treatment. Table 14 shows the fever experienced by calves in the different groups. In the groups vaccinated with live virus, the duration of fever above 40ºC (104ºF) was reduced in calves treated with interferon. Table 15 shows that seroconversion and GMT of BVD antibodies were significantly improved in calves treated with interferon.

When interferon is to be administered to animals simultaneously with the administration of a vaccine, the two may be administered separately or mixed together. (The term simultaneous as used here and in the claims means administration within a few minutes of the same time, not necessarily at the same exact second.) When mixed together, the formulation may be the same as standard vaccine formulations (which comprise a suspension of attenuated or killed microorganisms suitable for inducing immunity to an infectious disease). Such vaccine formulations are well known to one skilled in the art. The only variation would be the addition of the necessary amount of a biologically active interferon. Such formulations may comprise pharmaceutically acceptable carriers such as phosphate buffered saline (PBS).

Claims (9)

1. A combination preparation for vaccinating a warm-blooded vertebrate, comprising: a vaccine to induce immunity against an infectious disease, and at least one dose of a biologically active interferon in a dosage form for oral administration in an amount of not more than 5 IU interferon/lb (11 IU/kg) of vertebrate body weight per dosage unit, wherein the combination of vaccine and interferon dose are optionally in a form for separate administration. 2. Combination preparation according to claim 1, characterized in that the vaccine is in a form for oral administration and contains the interferon dose. 3. Combination preparation according to claim 1, characterized in that the interferon is produced by the leukocytes. 4. Combination preparation according to claim 1, characterized in that the interferon is human α-interferon. 5. A process for the manufacture of a preparation for oral use in a method for increasing vaccine efficacy in a warm-blooded vertebrate, characterized in that characterized in that interferon and a pharmaceutically acceptable carrier are combined for oral administration, wherein the interferon is present in an amount of not more than 5 IU/lb (11 IU/kg) of vertebrate body weight. 6. The method according to claim 5, characterized in that the interferon is α-interferon. 7. Use of interferon for the manufacture of a medicament for oral administration comprising interferon in a unit dosage amount of not more than 5 IU/lb (11 IU/kg) body weight for use in a method of enhancing vaccine efficacy in a warm-blooded vertebrate by administering the medicament together with the administration of a vaccine. 8. Use according to claim 7, characterized in that interferon produced by leukocytes is used. 9. Use according to claim 7, characterized in that α-interferon is used as interferon.